Editor’s pickThe Smile – A development in hardwood CLT

16-07-2017
American Hardwoods,CLT,AHEC,The Smile

By World Hardwoods

Although Cross Laminated Timber (CLT) is not new, high-rise buildings are now popping up all over the world, showing the environmental way for a new age of wood. Well-known Dutch architect Alex de Rijke recently predicted in an article entitled, “Timber is the New Concrete”, that timber would be the dominant construction material of the 21st Century.

So what was special about The Smile, a dramatic structure installed in the courtyard of Chelsea College of Art, for the London Design Festival 2016, which was designed by architect Alison Brooks with engineer Arup in cooperation with the American Hardwood Export Council? Made of timber, the structure effectively a beam curving up at both ends, was called The Smile and looked just like one.

Many considered it one of the most exciting installations of the festival. However to David Venables, European director of AHEC, it is clear that in his terms it was not just an installation, but something far more important. “It was meant to represent the challenges of a building.”

While CLT is becoming a widely accepted means of building, it has been done exclusively in softwood so far. The big difference for the construction industry here is that this was the first time hardwood had been used for CLT, already leading to commercial projects where strength and an improved appearance are key issues. Tulipwood is an abundant, lightweight but strong hardwood, so The Smile was the culmination of an effort to show that it can have a structural use in buildings. AHEC has been experimenting with tulipwood, most particularly in the design and making of the Endless Stair, a project for the London Design Festival two years ago, designed by architect dRMM and Arup.

“We learnt so much from the Endless Stair that we were able to take it forward to industrial production,” Venables explained. Whereas the Endless Stair used tulipwood CLT that had been prototyped for the occasion in a kind of hand-crafting approach, The Smile was made by German company Zueblin using an actual manufacturing process that is an adaptation of the way that it makes softwood CLT commercially.

There is a double win for tulipwood; firstly an abundant, naturally grown hardwood and secondly that CLT uses its lowest grades. The Smile makes the elements work as hard as they possibly can. It is a massive challenge in terms of scale and engineering as well as a demonstration of just how exciting and beautiful a building using hardwood CLT can be.